/*
 * Copyright 2020-2030 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.extraty.question14;

/**
 * @author Created by Neil Wang
 * @version 1.0.0
 * @date 2021/9/1 4:31 下午
 */
public class Solution3 {
    public String longestCommonPrefix(String[] strs) {
        int minLength = minLength(strs);
        int low = 0;
        int high = minLength;
        while (low < high) {
            int mid = getNextMid(low, high);
            if (isCommonPrefix(strs, mid)) low = mid;
            else high = mid - 1;
        }
        return strs[0].substring(0, low);
    }

    private int getNextMid(int low, int high) {
        return (high - low + 1) / 2 + low;
    }

    private int minLength(String[] strs) {
        int minLength = Integer.MAX_VALUE;
        for (String str : strs) {
            minLength = Math.min(minLength, str.length());
        }
        return minLength;
    }

    public boolean isCommonPrefix(String[] strs, int length) {
        String str0 = strs[0].substring(0, length);
        for (int i = 1; i < strs.length; i++) {
            for (int j = 0; j < length; j++) {
                if (str0.charAt(j) != strs[i].charAt(j)) return false;
            }
        }
        return true;
    }
}
